


gaster? more like sinster

by nhoneywhisky



Category: Undertale (Video Game)
Genre: Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tongue (Undertale), F/M, Other, Sexual Content, Smut, We're All Sinners
Language: English
Status: Completed
Published: 2020-02-09
Updated: 2020-02-09
Packaged: 2021-02-28 02:14:59
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 684
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22636579
Author URL: https://archiveofourown.org/users/nhoneywhisky/pseuds/nhoneywhisky
Summary: you have sex with w.d.gaster
Relationships: W. D. Gaster & Reader, W. D. Gaster/Reader
Comments: 9
Kudos: 36





	gaster? more like sinster

**Author's Note:**

> second smut, i'm going to hell  
> if you find any errors, feel free to tell me
> 
> reader has a vagina, no pronouns used

„How do you feel about being tied up?“, Gaster almost whispert into your ear with his dark and raspy voice. You are sitting on your bed, Gaster behind you. Your back leans against his chest and his hands are holding your wrists in your lap.

You actually just took a shower and are only wearing a white shirt and your underwear, when you find him sitting on your bed with a mischievous grin, lust hazed eye lights and holding a pair of leather hand cuffs. They look rather nice actually.

„I don’t mind them, i-i actually like t-them.“, is you answer, thinking about Gaster tying you up exciting you. Gasters hands are cuffing your wrists on your lap and you can feel your heart beating faster. 

His chest gives out a little rumble that you assume is a chuckle, while he strechtes your arms above your and behind his skull. His teeth are on your sensitive skin of you neck, giving it little nips and suddenly you can feel his cool tongue licking up to your ear.

Your body shivers at this and try to move your arms only for his tongue to lick over your throat. You breath hitches as his hands wander over your shirt to your waist, stomach and finally your breasts. You couldn’t stop a sudden moan escape your lips as he finds your nipples and rolls them between his warm fingers.

He stops after some minutes but only to play with you again under your shirt. Gaster summons another pair of hands who slide over your naked legs up to your underwear. Another, more desperate, moan escapes your lips as one of his extra hands finds your already soaked, clothed and pulsing folds. 

You arch your back and lay your head against his chest, closing your eyes. You couldn’t resist the urge to struggle more as his hands slip under your underwear and touches your desperate slick lips. You give out a shaky whimper when he touches your sensitive nub and rubs gently at it. 

„You’re so wet for me, y/n, you’re so perfect and the noises you make..“, Gaster himself growls and rubs his already materialized, magic dick against your ass. You moan his name as he dips two phallanges at the same time into you, making you cry out in pleasure. His other hands unbuckling his black jeans and tossing it to the ground.

He raises your legs by your thights and rubs his glowing dick between your legs, coating him with your arousal. 

„Who do you belong to? Say my name.“, he deeply growles into you neck as he lines up his twitching erection against your entrance. He pushes himself inside you at once, making you cry out his name so loud that you neighbours probably know what you’re up to right now.

He gives you some moments to adjust to his size and starts playing and massaging your breasts again.  
You try to wiggle your hips telling him that he can move again. Gaster didn’t wait to grab your thights and move you up and down his shaft. He grunts at the sensation and thrusts as deep as he can get while on of his extra hands fiddles with your pulsating clit.

He bites down into your shoulder, drawing blood and marking you, all while his thrusts get more and more erratic. The pleasure and pain mixture is everything you need to reach your climax and end as a moaning and shivering mess. 

Your body going limp as Gaster licks your wound clean and your quivering walls, body heat and whimpers make him lose his cool (lol). Moaning under his breath into your hair he let your cunt milk every drop of him. After he's done he grabs your arms and frees your wrists from the handcuffs. 

You stretch your limbs and smile up at Gaster satisfied, snuggling up to his chest. Your lover makes a quick job of cleaning you with a towel before pulling a blanket over you both.

„Good night, my love.“, he says, and you hum into his chest positively.


End file.
